As a charged particle beam apparatus capable of performing high-vacuum exhaust and low-vacuum exhaust, for example, there is a low-vacuum scanning electron microscope including a vacuum exhaust system disclosed in the following patent literature.
JP-A-2007-141633 (PTL 1) discloses a vacuum exhaust system that is capable of performing high-vacuum exhaust and low-vacuum exhaust of an electron gun chamber using minimum pumps and that has a configuration including a first pump (a turbo molecular pump) performing high-vacuum exhaust of the electron gun chamber and a second pump (an oil rotary pump) performing back pressure exhaust of the first pump and low-vacuum exhaust of a sample chamber as well.
JP-A-2011-034744 (PTL 2) discloses an exhaust system that includes a plurality of intermediate chambers through which electron rays pass between an electron gun chamber and a sample chamber, includes valves in openings between the plurality of intermediate chambers, and performs exhaust so that pressures of the intermediate chamber closer to the sample chamber than the value and the sample chamber are higher than pressures of the intermediate chamber closer to the electron source than the valve and the electron gun chamber in order to achieve an improvement in a throughput from sample exchange to observation since it is general to expose the sample chamber, the intermediate chambers, and the electron gun chamber to the atmosphere at the time of exchanging a sample in the low-vacuum scanning electron microscope of PTL 1 or the like.